You could have `simple-grid%' implement the `equal<%>' interface. http://docs.racket-lang.org/reference/objectequality.html?q=equal%3C%25%3E#%28def._%28%28lib._racket/private/class-internal..rkt%29._equal~3c~25~3e%29%29
Vincent At Sat, 28 Jul 2012 19:35:47 -0700, Gregory Woodhouse wrote: > > Okay, this is really a newbie question, but here goes. I have a class that > represents a Sudoku grid. Internally, the grid is stored as a vector of > vectors of integers: > > (define simple-grid% > (class object% > > (super-new) > > ;b is an internal representation of the grid and is initialized to an > empty grid > (define b(make-vector 9 (make-vector 9 0))) > > (define/public (get-cell r c) > (let > ([row (vector-ref b (sub1 r))]) > (vector-ref row (sub1 c)))) > > ;etc. > > > I provide methods get-cell to retrieve the contents of a single cell, > set-cell! to (destructively) update the contents of a cell and so forth. In > principle, I could implement equal? by looping all 81 cells and comparing > them one by one, but this seems awkward. It seems like I ought to be able to > just check that the state vectors are equal? but I have no access to b > outside the class. In Java, I'd add a protected method getStateVector that > could be called from within a separate method named equalTo that tells me if > a grid object g1 is equivalent to a g2. Or at least I could do this. I really > don't want to expose how the internal representation of the grid to other > classes. Then again, maybe that's Java thinking in the context of Racket. > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
